you can very easily buff their stats by editing the ship_data.csv file. hull points, armor, flux stats, speed, maneuverability, etc all work well for this, without having to mess with any mechanics or scripts.
that's what i did (along with increasing costs as well), because i agree they're overall not as powerful anymore as i like them to be. but if hull regen specifically is something that can be kinda exploited, maybe it really should be removed. it's not like that's the only thing that can make Templar ships powerful. ^^